How to detect missing bool field in json post data

When unmarshaling a json post into a struct, missing fields for bools will always unmarshal to a false value.

Is there a way to detect if there are missing fields in the json post data?

Thanks in advance.

I think you’re looking for something like the inverse of this -

Not hard to implement - what do you want back? Just a []string of the struct members that don’t have matching JSON keys/tags in the JSON object?

Maybe switch from a bool to a *bool might help you.

func main() {
	type test struct {
		Field1 *bool `json: "field1"`
	var test1, test2, test3 test

	json.Unmarshal([]byte(`{"field1": true}`), &test1)
	fmt.Println(test1.Field1, *test1.Field1) // 0xc82000a388 true

	json.Unmarshal([]byte(`{"field1": false}`), &test2)
	fmt.Println(test2.Field1, *test2.Field1) // 0xc82000a3a8 false

	json.Unmarshal([]byte(`{}`), &test3)
	fmt.Println(test3.Field1) // <nil>

If you just want to “hide” the missing fields, you could probably use the omitempty notation in your struct, like:

SomeData string `json:",omitempty"`

Here ya go …

Thanks for the responses chaps. Helps a lot.

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